1. Field of the Invention
This invention relates to the treatment of products, in particular, foodstuffs or food products. The invention relates especially to product treatment systems, in particular systems for the treatment of foodstuffs or food products, in which product-carrying units supporting the product or products to be treated are accommodated within a product treatment chamber. The invention is especially directed to a product-carrying unit for use in a product treatment chamber to facilitate enhanced or accelerated freezing of packaged food products supported on the unit. The invention further encompasses product treatment systems and product treatment chambers comprising product-carrying units according to the invention for use in treatments such as freezing, chilling, rendering or humidification.
2. Description of the Prior Art
Product treatment chambers for the treatment of food products are well-known, as also are a variety of product-carrying units for supporting packaged foodstuffs undergoing treatment, in particular freezing, within such chambers. Numerous prior art systems provide chambers of significant transverse dimension within which the packaged foodstuffs are supported on product-carrying units, which may be referred to as planks or shelves, extending across the lateral dimension of the chamber. In one such construction; the floors or surfaces of these product-carrying units are supported on transverse members of channel or I-beam cross-section, which, in use of the units, extend across the chamber between slideways provided on the side walls of the chamber, the webs of the channels or I-beams being vertical and their lower flanges being carried on the slideways or support members of the side walls at the longitudinal ends of the transverse members. Where the transverse dimension of the chamber is substantial, these reinforcing cross members of the unit, underlying the shelf floor, are of significant cross-sectional dimensions and weight, to carry the substantial weight of the packaged foodstuffs supported on the shelf and to provide a structure which is self-supporting across the extended transverse width of the chamber. The shelf floor may be corrugated, to provide additional strength and minimise the likelihood of snap freezing, but the corrugated material forming the floor is typically substantially continuous and impermeable to the passage of air, either through the floor from above to below or vice versa, and also from front to rear through the corrugations.
Similar product-carrying units of lesser dimensions are also known, where the unit in use again spans the transverse dimension of the product treatment chamber between supporting rails or slideways disposed on the inner sides of side walls of the chamber. The provision of transverse I-beam or channel section cross members of significant dimensions and strength is avoided in these smaller supporting units by providing an internally stiffened or self-reinforcing structure, which is however of substantially solid construction, being substantially impermeable to the passage of air in the direction of any of its dimensions, whether front to rear, transverse width, or depth. In use of both of the foregoing two known constructions of shelf, the shelves are loaded into the product treatment chamber or store in edge to edge abutting manner, so that a continuous sequence of abutting shelves is provided on each tier or level of the product treatment chamber or store. The close abutment in substantially edge to edge manner of these juxtaposed shelves on each tier of the storage chamber substantially prevents movement of air from tier to tier within the store, at any location other than the store ends. Thus, in carrying on a product treatment operation in a store or chamber accommodating units of the kind indicated in the foregoing paragraphs, there is substantial stratification of air movement, so that air entering the chamber at one end for the purposes of, for example, cooling or freezing food product accommodated on the shelves, is constrained to pass to the other end of the store substantially at the level or tier at which it enters, there being no significant possibility of air movement through the shelves to a level or tier above or below the particular airflow passage defined between a particular sequence of shelves and the sequence above or below it.
A further construction of product accommodating unit is also known, in which a multiplicity of shelves is provided within a single unit, referred to as a so-called xe2x80x9cbookcasexe2x80x9d. The bookcase unit may have typically nine shelves disposed one over the other and the entire bookcase is moved through the storage treatment chamber or store, within which it is supported on lateral slideways or support rails. Again bookcase units are moved through a treatment chamber or store from end to end by bringing them into abutting or juxtaposed contact in which each level or tier of shelves again defines a substantially self-contained airflow region for air movement from end to end within the store, without any significant possibility of transfer of air to other levels within the chamber during a treatment operation.
This absence of the possibility of circulation of air to different levels within the store constrains to a certain degree the efficiency with which heat exchange may be effected within the chamber, whether for freezing or for any other heat exchange purpose. In a product treatment chamber of the type within which product-carrying units of the kind recited above are accommodated, cold air is driven through the store to typically chill or freeze food product accommodated on the shelves. The greater the degree of contact which can be effected between the cooling heat exchange medium or air and the food product, which is typically packaged, the more effective the product treatment. Precisely the same applies in the case of a heat treatment operation or any other similar process step. The efficiency of heat exchange is limited in stores of the kind recited above due to the relative stratification of airflow so that the air passes through particular tiers or levels of the loaded storage chamber as separate streams of heat exchange medium and also due to the inability of the cooling air to come in contact with the underside of the product to be treated, in the case of the product being accommodated on a substantially solid or air-impermeable shelf. Depending on the type of product-carrying unit used, airflow within a particular tier or level may also be substantially laminar, with little turbulence being present, so that the efficiency of heat exchange may also be constrained for this reason.
EP-B1-0,474,514 of the present Applicants provides a product treatment chamber and storage system, as well as a product-carrying unit for accommodation in the chamber or storage system, in which the product-carrying units have edge regions extending along two opposite sides for travelling engagement with respective guide and support rails defining guide means for travelling movement of the unit. This European Patent describes an arrangement for coupling the product-carrying units together, in particular in a chamber structure in which parallel pairs of guide rails are provided on the internal side walls of the chamber. Irish Patent Specification No. 78447, also of the present Applicants, provides a variant of this product-carrying unit in which the floor of the pallet is apertured or perforated, or formed from a mesh material. Finely apertured or mesh materials are however undesirable in certain applications for reasons of hygiene and ease of cleaning.
It is an object of the present invention to provide improvements in facilitating accelerated, enhanced or expedited treatment of foodstuffs supported on a product-carrying unit in a product treatment chamber of the kind discussed above, in particular for the freezing of such products. It is a particular object of the invention to provide an improved product-carrying unit of the kind described by EP-81-0,474,514, but the invention is not limited to such units and may also be applied to the known shelf structures and chambers of the prior art. It is a further objective of the invention to provide for improved heat exchange with product supported on such units in a construction which is compatible with the hygiene and cleaning requirements of product treatment systems for foodstuffs in particular.
According to the invention in a first aspect, there is provided a product-carrying unit for use in a product treatment chamber, the unit having:
side portions extending along two opposite side regions of the unit for engagement with respective support features of a product treatment chamber, and
a floor region for the support of product, said floor region extending between said side portions and comprising a multiplicity of floor region portions together defining a discontinuous upper product-supporting surface of the unit,
wherein spaces defined between at least some of said multiplicity of floor region portions provide access to an underside region of product disposed on said discontinuous upper product-supporting surface of the unit for heat exchange contact between a heat exchange medium and said underside region,
characterised in that
said floor region is shaped to define means for directing flow of heat exchange medium towards said spaces for said heat exchange contact between a heat exchange medium and said underside region.
Said floor region may be shaped to define duct regions for the passage of a heat exchange medium substantially between a region in the vicinity of one edge portion of the unit extending between said side portions of the unit and a region in the vicinity of another edge portion of the unit also extending between said side portions, said spaces or vents communicating between said duct regions and said upper product-supporting surface of the unit. Access to said duct regions for at least ingress of heat exchange medium is preferably provided on the lower side of the unit intermediate said edge portions of the unit.
In a favoured embodiment, said floor region comprises a multiplicity of rib members extending between said edge portions in a direction substantially parallel to said side portions, upper surface regions of said rib members defining said discontinuous upper product-supporting surface of the unit, said duct regions being defined between said rib members.
The invention thus suitably provides a structure of significant strength capable of carrying in particular cased food products to be frozen, with the unit supported only at its ends or side edges, so that there is a clear unobstructed space across the width of the treatment chamber within which the unit is located for the turbulent flow of chilled air, together with passage of the cooling medium through ducts defined between ribs, for chilling contact with the undersides of the cases, thereby engendering especially effective and speedy chilling action.
In an especially preferred construction, said rib members slope downwardly from one of said edge portions of the unit towards the other of said edge portions of the unit. A stop feature for restraint of product supported on the unit may provided at said other of the edge portions of the unit. Suitably, said rib members terminate at said one of the edge portions of the unit at a level above that of the upper edge of a cross-member defining said one of the edge portions, and the upper surfaces of said rib members are sloped downwardly in the vicinity of said one of the edge portions to define a ramp portion extending from said upper edge of said cross-member to the level of said discontinuous upper product-supporting surface of the unit, i.e. between said upper edge and said product-carrying surface. In a preferred embodiment, said rib members are substantially frustoconical in cross-section in the direction extending between said edge portions of the unit.
In a particularly favoured construction, said rib members are defined by upstanding folded regions of an initially planar material portion and the rib members are substantially uniformly spaced from one another by remaining intervening planar sections of said initially planar material. Access to said duct regions for at least ingress of heat exchange medium is then suitably provided by apertures or vents in said remaining intervening planar sections of said initially planar material.
The unit according to the invention may further comprise means provided on at least one edge portion of the unit extending between said side portions of the unit for spacing the unit from a like unit engaged on the same support features of a product treatment chamber to provide a space between said unit and said like unit for the passage of heat exchange medium through said space between said unit and said like unit between an air flow region within the chamber above said unit and said like unit and an air flow region within the chamber below said unit and said like unit.
In a second aspect, the invention may then provide a product-carrying unit for use in a product treatment chamber, the unit having:
side portions extending along two opposite side regions of the unit for engagement with respective support features of a product treatment chamber, and
a floor region for the support of product,
characterised in that
means are provided on at least one edge portion of the unit extending between said side portions of the unit for spacing the unit from a like unit engaged on the same support features of a product treatment chamber to provide a space between said unit and said like unit for the passage of heat exchange medium through said space between said unit and said like unit between an air flow region within the chamber above said unit and said like unit and an air flow region within the chamber below said unit and said like unit.
Said spacing means is suitably provided on each edge portion of the unit extending between said side portions of the unit and may be defined by means for coupling said unit to said like unit.
The unit according to the invention is especially suited to an embodiment in which said side portions provide for travelling engagement with said support features, and said support features comprise guide and support rails disposed on opposite internal side walls of a product treatment chamber, but the invention may also be applied in chambers in which alternative support arrangements prevail.